1. Technical Field
The present invention relates to an optical disk drive and a method for recording data, and more particularly to a method for recording user data on a multilayer optical disk.
2. Related Art
In addition to including a play-only DVD of single-sided single layer type, DVDs include a play-only DVD of single-sided double layer type, rewritable single-layer or double-layer DVD±R or DVD±RW, and the like. In a double-layer DVD, tracks are created from an inner radius toward an outer radius in both first and second layers. There may be a case where tracks are created from the inner radius toward the outer radius in the first layer, and in the second layer tracks are created reversely from the outer radius to the inner radius.
In such a double-layer DVD, when user data are recorded in the first layer, there is conceivable a case where data recording is terminated at any point in a data area of the second layer or without recording data on the second layer at all, and an unrecorded area is left in a data area of the second layer. Thus, in a state where data are recorded only in the first layer and no data are recorded in the second layer, compatibility with the play-only DVD of double layer is not maintained (data are recorded in both the first and second layers of the play-only DVD), and difficulty is encountered in playing the user data recorded in the first layer by means of a play-only drive.
JP 2005-93032 A points out the above drawback and describes performance of processing pertaining to a corresponding unrecorded area data filling process of determining whether or not recorded areas are present in at least a data area of the first recording layer; and, when the recorded area is present in the first recording layer, recording dummy data in an unrecorded area in a region located at the same radial position as that of the recorded area in the second recording layer exclusive of the first recording layer at predetermined timing before completion of recording of data in the optical disk. There is also described that, in a case where a data recording request issued by the user has been received during background format processing when the optical disk is formatted in the background, formatting operation performed in the background is interrupted, to thus record dummy data.
FIG. 5 shows a flowchart of related-art processing. Provided that a first recording layer (a first layer) is taken as L0 and that a second recording layer (a second layer) is taken as L1, user data are recorded first in L0 (S101). After recording of user data, a determination is made as to whether or not an area of L1 located immediately above or below a recorded area of L0 remains unrecorded (S102). When the area does not remain unrecorded, compatibility with the play-only disk is maintained, and hence data in the area can be played, in unmodified form, by means of a play-only device (drive) (S104). Meanwhile, when an unrecorded area is determined to be present in L1, predetermined dummy data are recorded in a corresponding area of L1, thereby converting the unrecorded area into a recorded area (S103). After compatibility with the play-only disk has been maintained, the optical disk is played by means of the play-only drive (S104).
However, a problem of determination processing and dummy data writing operation involving consumption of time arises in connection with the configuration of determining whether or not an area of the second layer located immediately above or below the recorded area of the first layer remains unrecorded after completion of recording of data in the first layer, and recording dummy data into an unrecorded area of the second layer according to a result of determination. In relation to background processing, the same also applies to a case where dummy data are written by means of interrupting formatting operation when an optical disk is formatted. Since the time for writing dummy data is required, time is consumed from when data are finally recorded until when an optical disk can be ejected.